O2 heater control circuity: constant 12v or pulsed?

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Dec 10, 2003 | 12:03 PM

EE_Chris

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From: Severn, MD

O2 heater control circuity: constant 12v or pulsed?

On a stock ECU, does it supply a constant 12v to the heater section ALL the time, or is it a PWM signal?

What about the AEM EMS?

Dec 10, 2003 | 01:00 PM

JimBlake

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Re: O2 heater control circuity: constant 12v or pulsed? (EE_Chris)

The hot lead (+12v) comes from the main relay - NOT from the ECU. The ground leg of the heater circuit goes to the ECU. The ECU closes that leg to ground when it wants to run the heater. I don't really know if the ECU turns off the heater after it warms up...